RFID chip, gun safety device...
A simple RFID type chip or device that can secure the firearm & send a text alert or email to the gun owners smart phone is not a bad idea.
If the firearm is stolen or removed from a gun owner's property the RFID or tracer could help sworn LE or a service center track it's location(like GM's OnStar service).
A booby trap or anti-tampering device could be added too. If the crook or a child tampers with the firearm a loud alarm would sound or it could deliver a electrical charge.